In many devices which use integrated circuits, it is desirable to minimize power consumption. The more power consumed by an integrated circuit device, the greater the amount of heat generated. As integrated circuits continue to be miniaturized and circuit densities increase, reduction of power consumption becomes increasingly necessary to minimize heat dissipation and maintain acceptable operating temperatures. It is also desirable to minimize power consumption of integrated circuits in devices with a limited power supply, such as a battery, in order to maximize the operating time of such devices between charges.
For these and other reasons, many integrated circuits employ dedicated sleep modes or dedicated power-down modes in which at least some portion of the integrated circuit is temporarily shut down or operates with reduced functionality using less power. External commands are typically supplied to integrated circuit devices in order to enter and exit such dedicated reduced-power modes. However, it is also desirable to reduce power consumption in integrated circuits during active modes in which integrated circuits are expected to be fully operational. It is also known to save power by running systems at lower operating frequencies; however, this approach sacrifices significant performance.